1. Field of the Invention
The present invention relates to a ceramic composition for a magnetic head-supporting member (generally called "slider") to which magnetic pole pieces of a magnetic head used for an electronic computer are attached. More particularly, the present invention relates to a sintered ceramic body excellent in the cutting property and the chipping resistance.
2. Description of the Prior Art
In magnetic head-supporting members (referred to as "sliders" hereinafter), it is desired that the thermal expansion coefficient of the slider can be easily adapted to that of the magnetic head supported by the slider by changing the composition of the ceramic used for the slider. Since very small magnetic pole pieces are supported on the slider, very precise processing is necessary for the slider, and therefore, it is desired that the material of the slider should be stable against processing and be excellent in the processability. Namely, it is required that the resistance against grinding (cutting) should be low and the chipping resistance should be excellent.
As the slider material adaptable to Ni--Zn ferrite, there has been used forsterite or barium titanate, and the thermal expansion coefficient of this known slider material is substantially equal to the thermal expansion coefficient of Ni--Zn ferrite, which is 90 to 98.times.10.sup.-7 /.degree.C. However, when forsterite or barium titanate is used for Mn--Zn ferrite, since Mn--Zn ferrite has such as high thermal expansion coefficient as 100 to 120.times.10.sup.-7 /.degree.C., because of the difference of the thermal expansion between the slider material and Mn--Zn ferrite by the heat treatment of about 400.degree. C. at the glass-fusion-bonding step, cracking is caused or strain is left in the slider material and peeling of glass is readily caused during the processing. Accordingly, a forsterite or barium titanate type composition cannot be used for Mn--Zn ferrite.
Calcium titanate is used as the slider material that can be adapted to Mn--Zn ferrite. The thermal expansion coefficient of calcium titanate is substantially equal to that of Mn--Zn ferrite, which is 100 to 120.times.10.sup.-7 /.degree.C.
However, in a ceramic composed mainly of calcium titanate, chipping is readily caused at the machining step and the load resistance is large at the grinding step, and therefore, this material is defective in that the processability is poor.